Blalock, Glenn & Fontan Procedures

There are several different procedures that are used in the treatment of cardiac defects. Below are basic details for the most common ones which people with Down's Syndrome have done, but they are often modified to deal with the individual aspects of a patient's condition.

Blalock-Taussig (BT) shunt

This procedure was developed in the 1940's and is a palliative (temporary) treatment used to improve the blood flow to the lungs in conditions such as Pulmonary Atresia, severe Pulmonary Stenosis, Tricuspid Atresia, and severe Fallot's Tetralogy, until such time as the defect can be repaired.

This is usually a closed heart procedure which is carried out through an incision through the ribcage on the right or left of the child's back. The shunt (a small tube of synthetic material) is attached to one of the sections of the blood vessel to the arm and to the pulmonary artery making a direct connection between the aorta and the lungs (mimicking the ductus arteriosus). This allows more blood to flow to the lungs and improves the oxygen saturation levels (SAT's) relieving severe blueness (cyanosis) that the child may be experiencing.

With Fallot's Tetralogy a staged operation may be done depending on the baby's symptoms and oxygen saturations. This usually begins with a BT Shunt, than a complete repair at about six months which involves removing the pulmonary obstruction, closing the ventricular septal defect with a patch, and sometimes enlarging the pulmonary artery if needed.

A shunt is used for a limited period, usually up to six months, until the child outgrows it and a further shunt is necessary or a full repair is done. The child will need to take an anticoagulant such as aspirin to prevent clots blocking the shunt.

Glenn Procedure

This is another palliative (temporary) treatment used to improve the flow of blood to the lungs in complex conditions where only one ventricle is working properly and not enough blood is getting to the lungs.

It is an open heart procedure usually using the heart lung bypass machine and involves connecting the superior vena cava (which returns unoxygenated blood from the head and upper body to the lungs) to the right pulmonary artery thus taking the blood straight to the lungs for oxygenation without going through the heart. This increases the blood flow to the lungs and decreases the work of the heart. It will not work where there is pulmonary hypertension as the blood has to flow without the force of the heart pumping.

It is sometimes referred to as the Modified or Bi-Directional Glenn Shunt or a Cavo-pulmonary Shunt as the procedure performed now is a modified form of the original operation and it now supplies blood to both lungs, hence bi-directional.

The Glenn is usually one in a series of operations, done after the removal of a BT Shunt, or pulmonary artery banding, for example.

The Fontan Procedure

This type of surgery is used for children with complex congenital heart disease where the child cannot have surgery that gives them two pumping chambers and it usually undertaken at two to three years of age. It is designed to direct the blood coming back from the body directly to the lungs, without it being pumped there by the heart. Many patients will previously have had a bidirectional Glenn shunt.

The Fontan is an open heart procedure during which the unoxygenated blood returning from the lower part of the body is diverted directly to the pulmonary (lung) artery without passing through the right ventricle. This may be achieved in several different ways all of which connect the inferior vena cava directly to the lung artery, allowing the de-oxygenated blood flow to the lungs while the ventricle pumps the oxygenated blood to the body. The procedure relies on blood flowing to the lungs without the benefit of a pump so it is not suitable for patients with pulmonary hypertension (high lung artery pressure).

A list of reference sources used for this publication can be viewed on our website at www.dhg.org.uk/resources.aspx or you may call to request details in print.

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